The present invention relates generally to an optical fiber splicer for ribbon-shaped optical fiber cords which are widely used in an optical fiber communication circuit system. More particularly, the present invention relates to an optical fiber splicer of the foregoing type which can practically be used as an optical connector or an optical diverging/converging device.
To assure that a ribbon-shaped optical fiber cord composed of a plurality of optical fibers can be connected to an opponent ribbon-shaped optical fiber cord of the same type to make a reliable optical connection therebetween, an optical fiber splicer of the type including an aligning member and a cover member adapted to cooperate with the aligning member so as to allow sheathless optical fibers to be received in substantially V-shaped grooves formed on a flat working surface of the aligning member while extending in parallel with each other in the longitudinal direction when the aligning member and the cover member are assembled together has been developed and put in practical use.
To facilitate understanding of the present invention, a typical conventional optical fiber splicer of the foregoing type will be described below with reference to FIGS. 14 to 21.
FIG. 14 is a sectional view of a cover member 5, FIG. 16 is a sectional view of an aligning member 1 adapted to cooperate with the cover member 5 for firmly holding sheathless optical fibers 2 and 3 between the aligning member 1 and the cover member 5, and FIG. 18 is a sectional view of the conventional optical fiber splicer wherein the aligning member 1 is assembled with the cover member 5 while a plurality of sheathless optical fibers (four sheathless optical fibers in the illustrated case) 2 and 3 are firmly held between the aligning member 1 and the cover member 5. As is best seen in FIG. 21, four V-shaped optical fiber receiving grooves 4 are formed on a flat working surface of the aligning member 1 so that the sheathless optical fibers 2 and 3 are received in the grooves 4 in the longitudinal direction while extending in parallel with each other.
In addition, sheath receiving grooves 6 and 7 are formed on the aligning member 1 and the cover member 5 to receive sheaths 8 and 9 of ribbon-shaped optical fiber cords in the grooves 6 and 7.
In operation, the sheathless optical fibers 2 and 3 are first inserted into the optical fiber receiving grooves 4 from the opposite sides of the optical fiber splicer, and thereafter, the aligning member 1 and the cover member 5 are firmly assembled together in the presence of an adhesive coated on their flat working surfaces by the action of a compressing force imparted to the cover member 5 from above while the foremost end faces of the sheathless optical fibers 2 are brought in close contact with the foremost end faces of the opponent sheathless optical fibers 3 to make an optical connection therebetween.
With this construction, the outer peripheral surface of each of the sheathless optical fibers 2 and 3 comes in close contact with both the tapered surfaces of each V-shaped groove 4 in the form of a two-point contact, and a compressing force is then imparted to the cover member 5 from above so that the upper parts of the sheathless optical fibers 2 and 3 are compressed with a flat working surface of the cover member 5 by the action of the foregoing compressing force while the sheathless optical fibers 2 and 3 are correctly received in position in the V-shaped grooves 4. However, in case that the respective V-shaped grooves 4 are machined with some machining error or the respective sheathless optical fibers 2 and 3 are made with some fluctuation in outer diameter, there arises a malfunction that one or more sheathless optical fibers among the sheathless optical fibers 2 and 3 fail to come in contact with both the tapered surface of the V-shaped groove 4 or the flat working surface 10 of the cover member 5 as shown in FIG. 21.
For example, as shown in FIG. 21, sheathless optical fiber 2A does not come in contact with the right-hand tapered surface of the V-shaped groove 4, and the sheathless optical fibers 2C and 2D are unstably received in the V-shaped grooves 4.
Since the conventional optical fiber splicer is constructed in the above-described manner such that the sheathless optical fibers 2 are optically connected to the opponent sheathless optical fibers 3 with each V-shaped groove 4 as a reference, the aforementioned incorrect contact state is undesirable because there arises another malfunction that some of the sheathless optical fibers 2 are or will be positionally offset from the opponent optical fibers 3.
Incidentally, in case of single mode optical fibers, when a center axis of one optical fiber is positionally offset from that of the opponent optical fiber by a quantity of 1 .mu.m, it is found that the connection loss which has arisen at this time amounts to about 0.2 dB.
When the sheathless fibers 2 and 3 are more intensely squeezed in the V-shaped grooves 4 with the cover member 5 by the action of an increased magnitude of compressing force imparted thereto from above so as to cope with the foregoing malfunction, a higher stress appears in each of the sheathless optical fibers 2 and 3, resulting in the insert loss being increased. In this connection, another problem is that reliability and durability of the optical connection made between the foremost end faces of both the sheathless optical fibers 2 and 3 may be degraded due to the high stress derived from the intense compressing force.
With the conventional optical fiber splicer, since the aligning member 1 and the cover member 5 are assembled together to build the integral structure using an adhesive, an assembling operation is unavoidably complicated and time-consuming. For this reason, it is practically difficult to perform such an assembling operation as mentioned above in the field under bad outdoor working conditions.